凡在LINQ

Question

與陣列查詢我有數組編號= {2,3,4,5,6}

現在我不得不從表「dtlRecord」，其中此號碼是一個列選擇行。

 
Number count 
2  10 
3  23 
4  20

所以，我需要的是

select sum(count) from dtlRecord where number in (2,3,4,5,6) group by number 

我需要上面的LINQ查詢到SQL

Answer 1

如何只使用內部聯接：

int[] numbers = new[] { 2, 3, 4, 5, 6 }; 

from r in dtlRecord 
join number in numbers on r.Number equals number 
group r by r.Number into g 
     select new { 
      Number = g.Key, 
      Sum = g.Sum(r => r.Count) 
     }; 

或

dtlRecord 
    .Join(numbers, r => r.Number, number => number, (r, number) => new {r, number}) 
    .GroupBy(arg => arg.r.Number, arg => arg.r) 
    .Select(g => new 
    { 
     Number = g.Key, 
     Sum = g.Sum(r => r.Count) 
    }); 

Answer 2

LINQ等效凡
http://www.onedotnetway.com/linq-equivalent-of-where-in/

Answer 3

使用Enumerable.Contains作者：

int[] numbers = new[] { 2, 3, 4, 5, 6 }; 
var query = from r in dtlRecords 
      where numbers.Contains(r.Number) 
      group r by r.Number into g 
      select new { 
       Number = g.Key, 
       Sum = g.Sum(r => r.Count) 
      }; 

foreach(var result in query) { 
    Console.WriteLine("Number = {0}, Sum = {1}", result.Number, result.Sum); 
}